This invention relates generally to wireless communications, and more particularly to a system and method for profiling the location of mobile radio traffic across a coverage area served by one or more base transceiver stations.
Wireless communication technology has experienced unprecedented growth, fueled by advances in radio frequency, satellite, and microelectronic technologies and by the convenience of access to portable wireless devices. Several technologies have emerged for providing wireless communications, including analog systems such as Advanced Mobile Phone System (AMPS), and digital systems such as Global System for Mobile Communications (GSM) and Digital AMPS (D-AMPS). In general, such technologies fall into the class of xe2x80x9ccell-basedxe2x80x9d or cellular radio systems.
Cellular radio systems operate in interference-limited environments which rely on frequency reuse plans and Multiple Access techniques such as TMDA, FDMA, and CDMA, to maximize capacity. Because bandwidth and radio spectrum are limited resources shared by all users in the system, schemes to divide the available network bandwidth among as many subscribers as possible are often employed.
Currently, the volume of traffic in a system is estimated at the level of a base station coverage area by the use of Mobile Switching Center (MSC) statistics. To further determine the locations of traffic concentrations within a base station coverage area, service operators depend on customer complaints, drive tests, and visual inspections. For example, if a base station has a great deal of radio traffic on weekday mornings and evenings, and the base station covers a major highway between the city center and suburbs, it can be assumed that much of the radio traffic is coming from commuters on the highway. The locations of traffic concentrations can be measured only by a complex and expensive process involving use of a lower power Mobile Radio (MR) base station placed in areas of interest (e.g., near suspected concentrations) and by determining the fraction of mobile units that receive the signal strongly. A simple means of measuring the location of this traffic and identifying the areas of concentrations is lacking. Proposed solutions for identifying the positions of MRs when making emergency calls, for example, are complex or require specially-equipped MRs and, as such, are not suited to measuring large-scale traffic patterns.
At the same time, when the demand for network resources becomes great, and the volume of traffic on the system outpaces the capabilities of the network, the network manager may be required to make changes and/or redesigns in order to accommodate the increase in demand. There is currently no relatively simple and inexpensive technique for the location of MR traffic in a MR system. As such, geographic studies for the purpose of network analysis and possible improvement are needed so that traffic concentrations that might require additional capacity may be identified.
Specifically, until the present invention, there was no way to measure what percentage of traffic may be originating from one or more locations in a cell coverage area. Thus, if two major highways are serviced by one base station, there was no reliable way of determining what percentage of the total radio traffic is provided by each highway Such information would be useful in influencing system expansion plans.
Even when mobile positioning systems come into widespread use, it may not be easy to determine the positions of the MRs of interest, either because of the system congestion that would be caused by attempting positioning on every active MR in the coverage area, or because of privacy issues.
The present invention provides a method and system for profiling the location of MR traffic that does not require any data other than that which is already being gathered by the base transceiver stations. Using the invention, an operator may determine the locations where the MR traffic is concentrated and use the information gained to make system design decisions related to traffic handling. An example of a traffic-related problem would be an increase in the number of dropped calls or system access failures during periods of high traffic. If, for example, it could be established that a large portion of the traffic originates in a small area, the operator could consider establishing a micro cell to increase capacity in the area. One use of this invention is for making that sort of determination.
Disclosed is a method of profiling locations of MR traffic within a coverage area of a wireless communications network, the network including a plurality of base transceiver stations (BTSs) and one or more test measurement devices configured to make signal strength measurements from the BTSs to a plurality of points within the coverage area. The method comprises the step of causing the devices to make a set of signal strength measurements from a plurality of test sites contained within the coverage area. Next, the signal strength measurements are recorded and the BTSs are made to take a set of signal strength measurements for live MR traffic within the coverage area at any time when the distribution of MR traffic is desired. The test site signal strength measurements are compared with the MR signal strength measurements to determine if they match. If so, each match is recorded to determine the location of mobile traffic within the coverage area. If a match is not encountered, then the data is discarded.
The step of causing the devices to make a set of signal strength measurements can be performed at a plurality of locations, intervals and across all frequencies of interest within the coverage area. Preferably, they are performed at locations of potential interest within the coverage area. Also, a set of signal strength measurements can be made away from the location of the sites of potential interest in order to determine a falloff of intensity.
Also disclosed is a method of profiling MR traffic concentrations in a coverage area served by a plurality of BTSs within a wireless communications network. The method comprises the step of obtaining a set of calibration signal strength measurements for all BTSs within the coverage area. Next, signal strength measurements are made from all MRs within the coverage area and are compared to the calibration signal strength measurements to determine if they match. By obtaining a set of calibration signal strength measurements across all signal frequencies within the network, a plot of MR traffic concentration levels across the network can be obtained.
Further disclosed is a system for profiling the concentration of MR traffic within a coverage area of a wireless communication network. The system includes a plurality of BTSs located near or within the coverage area. At least one signal strength measuring device is provided and configured to measure the signal strength of each BTS from a plurality of locations within the coverage area. The system further includes a plurality of MRs serviced by the plurality of BTSs so that the serving BTS is able to request the MRs to measure and report the signal strengths of the BTSs as they communicate within the coverage area. The signal strength measuring device(s) can incorporate Global Positioning System (GPS) receivers.
A technical advantage of the invention is that it allows an operator to periodically monitor the geographical distribution of traffic to look for changes that might require adjustments in service and permits the network manager to pro-actively anticipate traffic-density problems.
Another technical advantage of the invention is the matching of calibrated signal strengths in various areas with those measured by active mobile units in the cell. This enables the geographical distribution of the callers to be determined at any time in order to diagnose traffic-related problems.